Characterizing linkage assembly

ABSTRACT

An improved characterizing linkage assembly of the type utilized to proportion the flow of fluids in response to motor controls, such as in the control of fuel and air mixtures in industrial combustion systems. The linkage system comprises a cam assembly having an adjustable curvilinear cam band, which is rotatable by a drive shaft. A biased follower rod is urged against the cam band, and upon movement thereby, pivots a linkage actuator arm which is bearingly supported on the drive shaft. Rotation of the drive shaft in response to a change in a selected process parameter imparts movement to the cam band, the follower rod and thus the linkage actuator arm in proportional travel.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to the field of fluid flow systems, andmore particularly but not by way of limitation, to an improvedcharacterizing linkage assembly for proportioning the flow of fluids inresponse to motor controls.

2. Discussion

In the control of fuel and air mixtures to industrial furnaces, boilersand the like, there is a need to maintain proper proportions of the fueland air over widely varying firing conditions. A number of prior artdevices are known for varying inlet fuel valving and inlet air ventingin response to monitored signals, such as temperature and stoichiometricparameters. For example, monitors are used to determine the free oxygencontent of a stack gas and to trim the inlet air as the monitoredreading varies from a set point.

As pointed out in numerous prior art publications, and as is known bypersons of ordinary skill in this field, each industrial burnerapplication will have numerous variables which take each suchinstallation beyond the range of prediction, and thus requiring thateach such installation be provided with the capability of tailoring itscharacterizing controls to its peculiarities over the range of itsfiring usage. Several prior art characterizing, or proportioningcontrols are as follow.

The patent issued to Maxon, U.S. Pat. No. 2,286,173, teaches a valve toproportion air and fuel to industrial burner systems in which an airgate is journaled in an air passage bore and is rotatable by a segmentalarm structure. A spring loaded stemmed valve (biased closed) issupported in a fuel inlet bore. A push rod is supported to engage thestemmed valve and is operable to open same as it is pressed against thestemmed valve. Actuating means is disposed to actuate the push rod bythe arm structure which supports a series of individually adjustablethreaded pins carried by the arm structure to variably depress the pushrod along the arc of the arm structure to vary the airfuel ratio. Aflexible strip is disposed between the push rod and the threaded pins tofacilitate engagement therewith.

The patent issued to Voorheis, U.S. Pat. No. 2,315,171, teaches anadjustable valve in which a series of adjusting screws provide a path toselectively depress a roller supported by an operating handle connectedto a valve rod which is spring biased. Thus the object of the invention,to move the valve control element through a predetermined sequence ofvalve settings, is achieved.

The patent issued to Condon et al, U.S. Pat. No. 3,706,438, teaches anoperating mechanism for controlling movement of a valve element. Acontinuous deformable channel has a pair of opposed cam surfacessupported by adjusting screws and a support member. A follower isconnected to a shaft which moves a valve element between open and closedpositions.

The patent issued to Spotz, U.S. Pat. No. 1,525,052, teaches anadjustable cam surface and a cam follower. The shape of the cam surfaceis determined by a plurality of adjustable struts which connect it to acarrying frame.

The patent issued to Tritle, U.S. Pat. No. 2,323,737 teaches a controlsystem having a cam that is mounted for pivoting on a pin and whichsections may be adjusted by means of screws.

None of these prior art control devices provide the advantages and thenovel structure of the present invention as described herein.

SUMMARY OF THE INVENTION

The present invention provides an improved characterizing linkageassembly which is used in a combustion system or the like in which amodulator motor, in response to a process parameter, actuates thelinkage assembly for the purpose of itself motoring other selectedelements, such as, for example, a fuel flow valve and combustion airinlet vanes.

The present linkage assembly comprises a drive shaft which is rotatablysupported by a support frame, the drive shaft being rotatable by themodulator motor. A linkage actuator arm is bearingly supported on thedrive shaft and has a follower arm portion extensive from a central hubportion of the linkage actuator arm. A follower rod is slidinglysupported by the support frame for reciprocal movement and is in pivotalengagement with the follower arm portion of the linkage actuator arm sothat movement of the follower rod rotates the linkage actuator arm onthe drive shaft.

The follower rod is spring biased toward engagement with a cam assemblywhich, upon rotation, serves to push the follower rod against itsbiasing spring. The cam assembly is attached to the drive shaft androtates in response to its rotation so that rotation of the drive shaftresults in movement of the follower rod which, in turn, imparts rotationto the linkage actuator arm.

The cam assembly has an adjustable cam band for forming an adjustablecurvilinear stop band rotatable with the drive shaft and which thespring biased follower rod is urged to follow in its proportionaltravel.

An object of the present invention is to provide an improvedcharacterizing linkage assembly which is of relatively simpleconstruction and which is readily adjustable to achieve proportionalcontrol of various process parameters.

Another object of the present invention, while achieving the abovestated object, is to provide an improved characterizing linkage assemblywhich is relatively inexpensive to manufacture, having a minimum ofcomponents and requiring conventional operations to manufacture, andwhich requires minimal maintenance while achieving acceptableperformance in such hostile environments that many industrial combustionsystems present.

Other objects, features and advantages of the present invention will beapparent from the following detailed description when read inconjunction with the drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a characterizing linkage assemblyconstructed in accordance with the present invention and depicted in atypical installation.

FIG. 2 is a side-elevational view of a portion of the cam assembly ofthe characterizing linkage assembly shown in FIG. 1; FIG. 2A is a topplan view thereof and FIG. 2B is a view taken at 2B--2B in FIG. 2.

FIG. 3 is a top plan view of one of the band gripping members of the camassembly portion shown in FIG. 2; and FIG. 3A is a view take at 3A--3Ain FIG. 3.

FIG. 4 is a view of one of the two band gripping members utilized togrippingly retain the opposing end portions of the flexible band shownin FIG. 2.

FIG. 5 is a partial, side-elevational view of the characterizing linkageassembly shown in FIG. 1; FIG. 5A is a partially detailed top plan viewof a portion of the characterizing linkage assembly shown in FIG. 5; andFIG. 5B is a partially cut-away front view of a portion of thecharacterizing linkage assembly depicted in FIG. 5.

FIG. 6 illustrates another installation in which the characterizinglinkage assembly of the present invention is utilized.

DESCRIPTION

In the following description, like numerals will be used to designatethe same components of the various drawing figures. Referring to thedrawings in general, and more particularly to FIG. 1, shown therein areas follows.

10 is a typical installation of the characterizing linkage assembly ofthe present invention.

12 is a support frame which typically will be attached to a conventionalburner assembly.

14 is a characterizing linkage assembly constructed in accordance withthe present invention. The characterizing linkage assembly 14 issupported on one end of the support frame 12; and

16 is another characterizing linkage assembly supported on the other endof the support frame 12. While the installation 10 illustrates a pair ofthe characterizing linkage assemblies, it will be appreciated that thepresent invention is not so limited, as the characterizing linkageassemblies can be used singly or in any combination.

18 is a pair of support arms extensive from the support frame 12.

20 is a rotatable drive shaft bearingly supported in aligned aperturesin the support arms 18.

22 and 24 are crank arms affixed to the drive shaft 20 and areconnectable via connector linkages 22A and 24B to primary/secondary aircontrol sleeves or other burner adjustments.

25A and 25B are crank arms affixed to the drive shaft 20 and connectablevia connectors 25C to a conventional modulator motor, an example ofwhich would be a control assembly which senses process parameters, suchas stack free oxygen among many other parameters, and pushes or pullsthe connector linkages 25C in a predetermined manner in response toprocess changes to rotate the drive shaft 20.

The characterizing linkage assemblies 14 and 16, supported at opposingends of the support frame 12, will now be described with reference toFIGS. 2 through 5B. Since the construction of these characterizinglinkage assemblies 14 and 16 ar essentially identical with the minorexception of the left/right locations of outboard components thereof, itwill be sufficient herein to describe one of these assemblies, with thecharacterizing linkage assembly 16 being arbitrarily selected. Thecharacterizing linkage assembly 16 is shown in partial detail in thementioned figures and comprises as follows.

26 is a cam assembly attached to near one end of the support frame 12and comprises:

28 is a cam support member having a plurality of radially extendingspaced apart radial slots 28A, and an access opening 28B.

30 is a hub portion having a slotted bore 30A and tightening bolt 30Bdisposed in appropriately placed apertures, the lower most one of whichis threaded so that the diameter of the bore 30A can be reduced once itis slipped over the drive shaft 20 to secure the hub portion 30 thereto;and

32 depicts a plurality of headed band support bolts, one for each of theradial slots 28A, and extending through apertures along the longitudinalaxis of each radial slot so that each band support bolt 32 is axiallydisposed along one of the radial slots 28A as shown. Each band supportbolt 32 is provided with a nut and spring washer 32A. Each nut 32A islocked to its band support bolt 32 with a thread locking compound. Thenut 32A rotates with the bolt 32 sliding on the spring washer to retainthe bolt 32 in the cam assembly 26.

34 depicts a plurality of band gripping members, each of which issupported by one of the band support bolts 32 and is disposed in arespective radial slot 28A. Each of the band gripping members 34 has abody portion with a threaded aperture 34A near one end and a bandengaging portion with a slot 34B at the other end. See FIGS. 3 and 3A.Each of the band gripping members 34 is supported by one of the bandsupport bolts 32 via its threaded aperture 34A and is positionable inits respective radial slot 28A. The band gripping members 34 can bemoved along their supporting band support bolts 32 to their desiredpositions by rotating the band support bolts 32.

36 is a flexible band member which is supported by the band engagingportions of the band gripping members 34. The thickness of the bandmember 36 is selected to be grippingly engaged by the slots 34B of theband gripping members 34 as shown. The width of the band member 36 isselected so as to extend outboard of the retaining slots 34B so that theband member 36 forms an adjustable curvilinear stop band for the purposedescribed hereinbelow. The shape of the band member 36 is adjusted byselectively positioning the band gripping members 34 along thesupporting band support bolts 32 to flex and retain the band member 36in a desired curvilinear configuration.

The opposing ends of the band member 36 are secured by a pair ofmodified band gripping members, one of which is depicted in FIG. 4 andcomprises as follows.

38 in FIG. 4 depicts one of the band gripping members, such having abody portion 38A similar to the body portion of the above described bandgripping members 34, which has a threaded aperture 38B supported on abolt 32 in an end one of the radial slots 28A as shown in FIG. 2. Theband gripping member 38 also has a hollow band gripping portion 38C, anda screw member 38D extensive into the hollow body portion thereof. Thescrew member 38D engages a threaded aperture in the end of a postportion 38E which extends into the hollow of the band gripping portion38C. This arrangement permits the band gripping portion 38C to berotatable on the post portion 38E with a change of angle of the flexibleband member 36 while securing the band member 36 relative to the face ofthe cam support member 28. A slot 38F is provided through one end of theband gripping portion 38C through which one end of the band member 36 isextended. Tightening of the bolt 38D assures that the end of the bandmember 36 is maintained within the slot 38F while allowing the band endsto slip through the slot when the length of the band changes due toincrease or decrease of the arc length.

The cam support member 28 is mounted on the drive shaft 20 and securedthereto via the bolt 30B. As the drive shaft 20 is caused to be rotated,it will be appreciated that the cam support member 28, and thus the bandmember 36, is caused to be rotated thereby. Since the slots 28A areradially disposed relative to the bore 30A, if the distance between theband member 36 and the center of the bore 30A is equal at each of theband gripping members 34 which grippingly retain the band member 36, thecurvilinear band member 36 will circumscribe a portion of a cylindricalsurface in its travel imparted by the drive shaft 20. However, withindividual adjustments made to the various band gripping members 34, theflexible band member 36 can be made to have a selected curvilinearcircumscription in its travel, an attribute utilized by thecharacterizing linkage assembly 16 for the purpose desribed hereinbelow.

FIGS. 5, 5A, and 5B show the details of the characterizing linkageassembly 16 as follows.

40 is another portion of the support frame 12 and comprises a supportplate attached to one end thereof. A supporting end plate 12A, having anappropriately disposed drive shaft clearance bore, can be provided asshown. A clearance apperture is provided in the support plate 40 forextension of the drive shaft 20 therethrough. The support plate 40 has apair of spaced apart tab members 40A which have a pair of axiallyaligned rod support apertures.

42 is a follower rod member which is slidingly supported by the rodsupport apertures in the support plate 40. That is, the follower rodmember 42 is slidable in opposing first and second directions asdepicted by the arrows 42A and 42B.

44 is a coil spring member which is disposed about the follower rodmember 42.

46 is a spring retainer member which is extensive through an aperture inthe follower rod member 42, and the spring member 44 is retained betweenthe spring retainer member 46 and one of the tab members 40A extensivefrom the support plate 40.

48 is a roller which is supported at the distal end of the follower rodmember 42 via a screw arbor 48A and threaded aperture in a threadedportion thereof. The spring member 44 biases the follower rod member 42in the first direction 42A and the roller 48 is restrained to be inrolling engagement with the surface of the band member 36 so that thefollower rod member 42 is caused to reciprocate in the first and seconddirections 42A, 42B when the curvilinearity of the band member 36 isappropriately adjusted by the band gripping members 34 supported on theband support bolts 32 of the cam assembly 26.

50 is another pin member which extends through, and is retained in, anaperture in the follower rod member 42.

52 is a linkage actuator arm having a central hub portion 52A with abore 52B. As mentioned above, the drive shaft 20 extends through anaperture in the support plate 40, and the bore 52B is sized so as toloosely receive the drive shaft 20 therethrough so that the linkageactuator arm 52 is supported by the drive shaft 20 while beingindependent to the rotational movement thereof.

54 is a linkage arm portion of the linkage actuator arm 52, and whilethe linkage actuator arm 52 can be of one piece construction, it isconvenient to attach the linkage arm 54 to the central hub portion 52Avia screws 54A which extend through selected holes of a circle of screwholes 54B. With the central hub portion 52A provided with a circle ofthreaded screw holes, the angular disposition of the linkage arm 54 canbe altered as desired by the mating of these screw holes in a desiredconfiguration and securing the linkage arm 54 to the central hub portion52A via the screws 54A.

56 is a follower arm portion of the linkage actuator arm 52 whichextends from the central hub portion 52A. The follower arm 56 has agenerally longitudinal slot 56A which extends radially relative to thecenter of the bore 52B and is disposed to loosely receive a portion ofthe pin member 50 which extends from the follower rod member 42.

In order to retain the linkage actuator arm 52 on the drive shaft 20,the follower arm 56 is positioned between the follower rod 42 and thesupport plate 40 with sufficient clearance to avoid interference betweenthese components. As the follower rod member 42 is caused to be moved inthe first or second directions 42A, 42B, the pin 50 causes the followerarm 56 to be moved to the left or right, which then causes the linkagearm 54 to rotate on the drive shaft 20.

Returning to FIG. 1, it will first be noted that the description of thecharacterizing linkage assembly 16 will also be applicable to thecharacterizing linkage assembly 14, both of which are disposed atopposing ends of the drive shaft 20. Therefore, the same numbers usedabove will depict like components of the characterizing linkage assembly14 in FIG. 1. For convenience of claiming, the term characterizinglinkage assembly will sometimes be used hereinbelow to refer to theassemblies 14 and 16 in combination as shown in FIG. 1 and FIG. 6.

Turning to FIG. 6, and again using the same numerals as above for likecomponents, shown therein are the characterizing linkage assemblies 14and 16 connected to opposing ends of the drive shaft 20. However, in theapplication depicted in FIG. 6, shown therein is:

58 is a motor control unit which supports the drive shaft 20 and whichimparts responsive rotary movement to the drive shaft 20. The motorcontrol unit 58 shown may be, by way of example, a Modutrol motorcontrol manufactured by Honeywell Corporation of Minneapolis, Minnesota.Modutrol is a trademark of that company and is the name of a productwhich contains at least one electronic transducer and a modulator motorfor imparting rotational energy to the drive shaft 20 in response toanalyzed data received from the controlled process. For example, in anindustrial combustion application, if the air and fuel mixture is notproper, or changes from an optimum setting, or a change in boiler loadis called for, the drive shaft 20 is caused to be rotated, which in turncauses the linkage arm 54 of the linkage actuator arm 52 to be rotated.The linkage arms 54, 56 of the characterizing linkage assemblies 14, 16may be connected to the louvers of an intake air conduit or to a fuelvalve. Normally, the assemblies 14 and 16 are connected to fuel valves,with one being a gas fuel valve and the other being an oil fuel valve,and the air intake is driven by another linkage. Since the shape of theflexible band member of each of the characterizing linkage assemblies 14and 16 can be independently configured to a desired curvilinear arc, thecharacterizing linkage assemblies 14 and 16, while acted onsimultaneously by the same drive shaft 20, can be caused to respond inthe movement of their respective linkage arms 54 independently to eachother.

The operation of the characterizing linkage assemblies 14 and 16 willhave become clear from the above description. It will be pointed outthat the characterizing linkage assembly of the present invention offersa number of advantages over the prior art in that a high degree ofresponse movement of the linkage arm 54 is achieved while minimizing thenumber of components and weight thereof, resulting in a low inertiaassembly which can be made with relatively quick rotational reversals.Also, the components are of relatively simple and open design, therebyaffording constant access for visual inspection and repair.

It is clear that the present invention is well adapted to carry out theobjects and to attain the ends and advantages as well as those inherenttherein. While presently preferred embodiments of the invention havebeen described for purposes of this disclosure, numerous changes may bemade which will readily suggest themselves to those skilled in the artand which are encompassed within the spirit of the invention disclosedand as defined in the appended claims.

What is claimed:
 1. A characterizing linkage assembly activated by amodulator motor and responsive thereto for proportionately motoringselected elements, the linkage assembly comprising:a support frame; adrive shaft bearingly supported by the support frame, the drive shaftrotatable by the modulator motor; a linkage actuator arm rotatablysupported by the drive shaft by a central hub portion thereof and havinga follower arm portion extensive from the central hub portion of thelinkage actuator arm; a follower rod slidingly supported by the supportframe for reciprocal movement in a first direction and in an oppositesecond direction, the follower rod disposed in pivotal engagement withthe follower arm portion so that movement of the follower rod rotatesthe linkage actuator arm; biasing means for biasing follower rod in thefirst direction; and cam means attached to, an rotatable by, the driveshaft and cooperating with the biasing means for moving the follower rodin the first and second directions in response to rotation of the driveshaft, the cam means characterized as comprising:a cam support memberhaving a hub portion having a bore and attachable to the drive shaftextensible through the hub portion bore; cam band means supported by thecam support member for forming an adjustable curvilinear stop bandrotatable with the drive shaft; and wherein the follower rod is biasedby the biasing means so that one end of the follower rod is slidablyrestrained along the stop band whereby the rotational position of thefollower arm portion and the linkage actuator arm is determined by therotational position of the drive shaft and the selected adjustment ofthe curvilinear stop band.
 2. The linkage assembly of claim 1 whereinthe cam support member is characterized as having a plurality ofradially extending, spaced apart radial slots, the cam support memberhaving a plurality of bores, each of such bores extending along thelongitudinal axis of one of the radial slots and communicating with itsrespective radial slot, and wherein the cam band means comprises:aplurality of threaded band support bolts each of which is disposed inone of the bores of the support member and disposed to extend the lengthof the respective radial slot associated therewith; a plurality of bandgripping members each of which has a body portion and a band engagingportion, the body portion having a threaded aperture engageable on oneof the threaded band support bolts and supported within the radial slotassociated therewith, the band engaging portion of each band grippingmember extensive from such radial slot along one side of the cam supportmember and having a band gripping slot disposed therethrough; and aflexible band member grippingly supported in the band gripping slots ofthe band gripping members, the curvilinear shape of the flexible bandmember determined by the disposition of the band gripping members on theband support bolts in the radial slots.
 3. The linkage assembly of claim2 further comprising a drive shaft cam member supported by the driveshaft, the drive shaft rotatable by force applied to the drive shaft cammember.
 4. The linkage assembly of claim 2 further comprising:driveshaft modulator means for selectively rotating the drive shaft inresponse to a selected measured process parameter.
 5. The linkageassembly of claim 4 further comprising:a second linkage actuator armrotatably supported by the drive shaft by a central hub portion thereofand having a follower arm portion extensive from the central hub portionof the linkage actuator arm; a second follower rod slidingly supportedby the support frame for reciprocal movement in the first and seconddirections, the second follower rod in pivotal engagement with thefollower arm portion of the second linkage actuator so that movement ofthe second follower rod rotates the second linkage actuator; secondbiasing means for biasing the second follower rod in the firstdirection; and second cam means supported by the drive shaft andcooperating with the second biasing means for moving the second followerrod in the first and second directions in response to rotation of thedrive shaft.
 6. The linkage assembly of claim 5 wherein the second cammeans comprises:a second cam support member having a hub portion havinga bore and attachable to the drive shaft extensible through the hubportion bore; and second cam band means supported by the second camsupport member for forming a second adjustable curvilinear stop bandrotatable with the drive shaft; and wherein the second follower rod isbiased by the second biasing means so that one end of the secondfollower rod is slidably restrained along the second stop band wherebythe rotational position of the second follower arm portion of the secondfollower arm is determined by the rotational position of the drive shaftand the selected adjustment of the second curvilinear stop band.
 7. Thelinkage assembly of claim 6 wherein the cam support member ischaracterized as having a plurality of radially extending spaced apartradial slots, the second cam support member having a plurality of bores,each of such bores extending along the longitudinal axis of one of theradial slots and communicating with its respective radial slot, andwherein the second cam band means comprises:a plurality of threaded bandsupport bolts each of which is threaded disposed in one of the threadedbores of the second support member and disposed to extend the length ofthe respective radial slot associated therewith; a plurality of bandgripping members each of which has a body portion and a band engagingportion, the body portion having a threaded aperture engageable on oneof the threaded band support bolts and supported within the radial slotassociated therewith, the band engaging portion of each band grippingmember extensive from such radial slot along one side of the cam supportmember and having a band gripping slot disposed therethrough; and aflexible band member grippingly supported in the band gripping slots ofthe band gripping members, the curvilinear shape of the flexible bandmember determined by the disposition of the band gripping members on theband support bolts in the radial slots.
 8. The linkage assembly of claim7 further comprising a drive shaft cam member supported by the driveshaft, the drive shaft rotatable by force applied to the drive shaft cammember.